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Farmani A, Omidniaee A. Observation of Plasmonics Talbot effect in graphene nanostructures. Sci Rep 2024; 14:1973. [PMID: 38263388 PMCID: PMC10805921 DOI: 10.1038/s41598-024-52595-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 01/20/2024] [Indexed: 01/25/2024] Open
Abstract
We report on the theoretical models of the plasmoincs Talbot effect in graphene nanostructure. The Talbot effect for the plasmonics applications in the IR range is theoretically studied and the respective Talbot effect for the novel advanced plasmonics structures are numerically investigated for the first time. It is shown that the metamaterial structures with periodic grating configuration represents a complex three-dimensional lattice of beamlet-like graphene plasmonics devices. The calculated results agree well with the experimental ones. The results obtained can be used to create and optimize the structures considering diffraction limit for a wide range of application areas. Effective focusing of plasmonic waves with exact focal spots and a subwavelength full width at half maximum can be obtained by using periodic graphene grating.
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Affiliation(s)
- Ali Farmani
- Department of Electronics Engineering, Lorestan University, Khoramabad, Iran.
| | - Anis Omidniaee
- Department of Electronics Engineering, Lorestan University, Khoramabad, Iran
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Dalal K, Sharma Y. Plasmonic switches based on VO 2as the phase change material. NANOTECHNOLOGY 2024; 35:142001. [PMID: 38100839 DOI: 10.1088/1361-6528/ad1642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 12/15/2023] [Indexed: 12/17/2023]
Abstract
In this paper, a comprehensive review of the recent advancements in the design and development of plasmonic switches based on vanadium dioxide (VO2) is presented. Plasmonic switches are employed in applications such as integrated photonics, plasmonic logic circuits and computing networks for light routing and switching, and are based on the switching of the plasmonic properties under the effect of an external stimulus. In the last few decades, plasmonic switches have seen a significant growth because of their ultra-fast switching speed, wide spectral tunability, ultra-compact size, and low losses. In this review, first, the mechanism of the semiconductor to metal phase transition in VO2is discussed and the reasons for employing VO2over other phase change materials for plasmonic switching are described. Subsequently, an exhaustive review and comparison of the current state-of-the-art plasmonic switches based on VO2proposed in the last decade is carried out. As the phase transition in VO2can be activated by application of temperature, voltage or optical light pulses, this review paper has been categorized into thermally-activated, electrically-activated, and optically-activated plasmonic switches based on VO2operating in the visible, near-infrared, infrared and terahertz frequency regions.
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Affiliation(s)
- Kirti Dalal
- Department of Electronics and Communication Engineering, Delhi Technological University, Bawana Road, Delhi, 110042, India
| | - Yashna Sharma
- Department of Electronics and Communication Engineering, Delhi Technological University, Bawana Road, Delhi, 110042, India
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Brozzesi S, Attaccalite C, Buonocore F, Giorgi G, Palummo M, Pulci O. Ab Initio Study of Graphene/hBN Van der Waals Heterostructures: Effect of Electric Field, Twist Angles and p-n Doping on the Electronic Properties. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:2118. [PMID: 35745456 PMCID: PMC9228424 DOI: 10.3390/nano12122118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 06/10/2022] [Accepted: 06/16/2022] [Indexed: 11/17/2022]
Abstract
In this work, we study the structural and electronic properties of boron nitride bilayers sandwiched between graphene sheets. Different stacking, twist angles, doping, as well as an applied external gate voltage, are reported to induce important changes in the electronic band structure near the Fermi level. Small electronic lateral gaps of the order of few meV can appear near the Dirac points K. We further discuss how the bandstructures change applying a perpendicular external electric field, showing how its application lifts the degeneracy of the Dirac cones and, in the twisted case, moves their crossing points away from the Fermi energy. Then, we consider the possibility of co-doping, in an asymmetric way, the two external graphene layers. This is a situation that could be realized in heterostructures deposited on a substrate. We show that the co-doping acts as an effective external electric field, breaking the Dirac cones degeneracy. Finally, our work demonstrates how, by playing with field strength and p-n co-doping, it is possible to tune the small lateral gaps, pointing towards a possible application of C/BN sandwich structures as nano-optical terahertz devices.
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Affiliation(s)
- Simone Brozzesi
- Dipartimento di Fisica and INFN, Universitá di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy;
| | - Claudio Attaccalite
- Centre Interdisciplinaire de Nanoscience de Marseille UMR 7325 Campus de Luminy, CNRS/Aix-Marseille Université, CEDEX 9, 13288 Marseille, France;
| | - Francesco Buonocore
- Energy Technologies and Renewable Sources (TERIN) Department, Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Casaccia Research Centre, 00123 Rome, Italy;
| | - Giacomo Giorgi
- Department of Civil & Environmental Engineering (DICA), Universitá degli Studi di Perugia, Via G. Duranti 93, 06125 Perugia, Italy;
- CNR-SCITEC, 06123 Perugia, Italy
| | - Maurizia Palummo
- Dipartimento di Fisica and INFN, Universitá di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy;
| | - Olivia Pulci
- Dipartimento di Fisica and INFN, Universitá di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy;
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Goudarzi K. Ultra-narrow, highly efficient power splitters and waveguides that exploit the TE 01 Mie-resonant bandgap. OPTICS EXPRESS 2021; 29:32951-32965. [PMID: 34809116 DOI: 10.1364/oe.438980] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/10/2021] [Indexed: 06/13/2023]
Abstract
In this paper, ultra-narrow and highly-efficient straight and Ω-shaped waveguides, and Y-shaped and T-shaped optical power splitters composed of two rows of two-dimensional germanium rods in air are designed and simulated. The position-disordering effect on the waveguides is considered. Finite-difference time-domain numerical simulation results for two rows of straight and Ω-shaped waveguides with no position disordering at the normalized frequency of a λ=0.327 show optical transmission of 90%, and two rows of Y-shaped and T-shaped power splitters with no position disordering have transmissions >46% for each output branch at the normalized frequency of a λ=0.327. Also, the straight and Ω-shaped waveguides with four rows of germanium rods tolerated position disordering of η = 10%. The proposed ultra-narrow waveguides and power splitters are vital components in high-density and all-dielectric optical integrated circuits.
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Tunable broadband polarization converters based on coded graphene metasurfaces. Sci Rep 2021; 11:1296. [PMID: 33446788 PMCID: PMC7809413 DOI: 10.1038/s41598-020-80493-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 12/22/2020] [Indexed: 11/28/2022] Open
Abstract
In this paper, two optimization algorithms (randomly initialized hill climbing and genetic algorithms) are considered to design broadband polarization converters based on coded metasurfaces. A pixeled graphene patch with an elliptic structure is proposed for the initial solution. Each pixel can be 1 and 0 which represents the presence and absence of the graphene. The initial guess tends to the optimum configuration after several optimization processes. Four broadband polarization converters are designed utilizing the optimization algorithms. By changing the chemical potential of graphene, the operation frequency of the polarization converters can be adjusted. Furthermore, the effects of relaxation time of graphene and incident angle on the polarization conversion bandwidth of the four designed structures are investigated.
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Rigosi AF, Levy AL, Snure MR, Glavin NR. Turn of the decade: versatility of 2D hexagonal boron nitride. JPHYS MATERIALS 2021; 4:10.1088/2515-7639/abf1ab. [PMID: 34409257 PMCID: PMC8370033 DOI: 10.1088/2515-7639/abf1ab] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The era of two-dimensional (2D) materials, in its current form, truly began at the time that graphene was first isolated just over 15 years ago. Shortly thereafter, the use of 2D hexagonal boron nitride (h-BN) had expanded in popularity, with use of the thin isolator permeating a significant number of fields in condensed matter and beyond. Due to the impractical nature of cataloguing every use or research pursuit, this review will cover ground in the following three subtopics relevant to this versatile material: growth, electrical measurements, and applications in optics and photonics. Through understanding how the material has been utilized, one may anticipate some of the exciting directions made possible by the research conducted up through the turn of this decade.
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Affiliation(s)
- Albert F Rigosi
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899, United States
| | - Antonio L Levy
- Physical Measurement Laboratory, National Institute of Standards and Technology (NIST), Gaithersburg, MD 20899, United States
| | - Michael R Snure
- Sensors Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433, United States
| | - Nicholas R Glavin
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson AFB, OH 45433, United States
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Gupta N, Savaliya PB, Dhawan A. Plasmonic nanoantennas on VO 2 films for active switching of near-field intensity and radiation from nanoemitters. OPTICS EXPRESS 2020; 28:27476-27494. [PMID: 32988041 DOI: 10.1364/oe.391655] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 06/30/2020] [Indexed: 06/11/2023]
Abstract
In this paper, we propose novel plasmonic switches based on plasmonic nanoantennas lying on top of a thin film of a phase change material such as vanadium dioxide (VO2), such that the near-field properties of these nanoantennas can be actively switched by varying the phase of the VO2 film. We employ finite difference time domain (FDTD) simulations to first demonstrate that the near-field intensity in the vicinity of the plasmonic nanoantennas can be substantially switched by changing the phase of the vanadium dioxide film from the semiconductor state to the metallic state. We demonstrate that a ring-bowtie nanoantenna (RBN) switch can switch the near-field intensity by ∼ 59.5 times and ring-rhombus nanoantenna (RRN) switch can switch the near-field intensity by a factor of ∼ 80.8. These values of the maximum intensity switching ratios are substantially higher than those previously reported in the literature. In addition, we optimize the various geometrical parameters of the plasmonic switches to maximize the intensity switching ratio and to understand how the different parameters affect the performance of the plasmonic switches. In this paper, we also show that the intensity of emission from a nanoemitter placed in the gap between the two arms of a plasmonic nanoantenna can be significantly switched by changing the phase of the VO2 film between its semiconductor state and the metallic state. To quantify the switching of emission from the nanoemitters placed in the near-field of the nanoantennas, we define and calculate a parameter, called FESR, the ratio of fluorescent enhancement factors in the on-state and off-state of the plasmonic switch. The maximum fluorescence enhancement switching ratio (FESR) of ∼ 163 is obtained for the RBN switch and FESR of ∼ 200 is obtained for RRN switch. The plasmonic switches being proposed by us can be easily fabricated by employing the conventional nanofabrication and thin film deposition processes.
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Ullah N, Liu W, Wang G, Wang Z, Khalid AUR, Hu B, Liu J, Zhang Y. Gate-controlled terahertz focusing based on graphene-loaded metasurface. OPTICS EXPRESS 2020; 28:2789-2798. [PMID: 32121959 DOI: 10.1364/oe.381765] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 01/10/2020] [Indexed: 06/10/2023]
Abstract
Metasurfaces have proven their great application potentials in terahertz (THz) wave modulations. However, realizing an active metasurface retaining lensing functionality in the THz frequency regime is still highly desired. Here a metalens, featuring electrically tunable focal length, based on propagation phase delay, is proposed and demonstrated experimentally. To have full control over the designed lens functionality, a gold thin film etched with a C-shaped aperture antenna array covered by monolayer graphene is used. By applying a bias voltage to the graphene, the phase control of the antenna array is changed, and thus the focus of the linearly polarized THz beam can be flexibly tuned from 7.13mm to 8.25mm. The proposed approach has a promising perspective for a variety of applications in communication, reconfigurable flat optics and real-time imaging in THz regime.
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Hajati M, Monfared YE. Modal properties of a cylindrical graphene-coated nanowire deposited on a hexagonal boron nitride substrate. APPLIED OPTICS 2019; 58:6666-6671. [PMID: 31503598 DOI: 10.1364/ao.58.006666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 07/25/2019] [Indexed: 06/10/2023]
Abstract
Due to complementary chemical and optical characteristics, structural integration of graphene and hexagonal boron nitride (hBN) can lead to a promising platform for development of novel plasmonic devices. In this paper, we numerically investigate the modal behavior of a cylindrical graphene-coated nanowire (GNW) deposited on a thin hBN (GNW-hBN) substrate in the mid-infrared range. Our studies revealed that GNW-hBN can support hybridized plasmon-phonon modes in the upper reststrahlen band of hBN, which mainly originates from the strong coupling between plasmon modes in GNW and phonon modes in hBN. The characteristics of these hybrid modes can be effectively tuned by changing the chemical potential of graphene, hBN thickness, and gap distance between GNW and hBN. According to the results, by choosing smaller gap distances and tuning the chemical potential of graphene, GNW-hBN can exhibit a fundamental mode (m=0, where m is the azimuthal mode number) with higher effective index such that Real(neff) varies from 131.2-62.3 when the hBN thickness changes from 2-20 nm. In addition, the presence of an hBN slab can break the azimuthal symmetry of the high-order graphene plasmon modes (m≥1) in the GNW-hBN structure.
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Asgari S, Shokati E, Granpayeh N. High-efficiency tunable plasmonically induced transparency-like effect in metasurfaces composed of graphene nano-rings and ribbon arrays and its application. APPLIED OPTICS 2019; 58:3664-3670. [PMID: 31044869 DOI: 10.1364/ao.58.003664] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 03/30/2019] [Indexed: 06/09/2023]
Abstract
In this paper, a plasmonically induced transparency (PIT)-like phenomenon in a metasurface composed of a periodic graphene ring and ribbon arrays is studied in the terahertz region. We used the Lorentz oscillator model to analyze the metasurface physically and theoretically. This PIT-like effect can be tuned by alternation of the chemical potential and dimension of the nano-graphene ring and ribbon. The resonance frequency of the PIT-like phenomenon is not sensitive to the incident lightwave angle. As an application of the structure, a refractive index sensor is proposed and simulated. Furthermore, we propose a metasurface composed of a double ring and graphene ribbon to realize the PIT-like effect with three dips. Our results express an appropriate approach for the expansion of mid-infrared absorbers and sensors.
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Baqir MA, Farmani A, Fatima T, Raza MR, Shaukat SF, Mir A. Nanoscale, tunable, and highly sensitive biosensor utilizing hyperbolic metamaterials in the near-infrared range. APPLIED OPTICS 2018; 57:9447-9454. [PMID: 30461991 DOI: 10.1364/ao.57.009447] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 10/08/2018] [Indexed: 06/09/2023]
Abstract
A plethora of research in recent years has been reported on biosensing in the surface plasmon resonant systems. However, very little research has reported a tunable and highly sensitive biosensor in a nanoscale platform. In this regard, we propose a nanoscale hyperbolic metamaterial (HMM)-based prism coupled waveguide sensor (PCWS) in the near-infrared range. The HMM layer makes up one of the constituents of the PCWS-comprised of a periodically arranged assembly of silver nanostrips. The structure is numerically simulated by the finite difference time domain method. It is demonstrated that the sensitivity of the reflected light can be tuned through the refractive index (RI) of the solution. Moreover, the effects of alteration of constituents of PCWS on the sensitivity have been analyzed. Results show that the sensitivity of PCWS can be harnessed by altering the thickness, slant angle of HMM layer, volume fraction (f) of metal in the HMM layer, and the incidence angle of light. For this purpose, the structure is numerically simulated by the finite difference time domain method. In the optimum design of the proposed sensor, the maximum value of sensitivity is achieved as high as S=3450 nm/refractive index unit with θ=10° and ϕ=10° and a metamaterial thickness of 250 nm. Moreover, the structure has a nanoscale footprint of 600 nm×400 nm×200 nm.
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Ye S, Wang Z, Sun C, Dong C, Wei B, Wu B, Jian S. Plasmon-phonon-polariton modes and field enhancement in graphene-coated hexagon boron nitride nanowire pairs. OPTICS EXPRESS 2018; 26:23854-23867. [PMID: 30184881 DOI: 10.1364/oe.26.023854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 07/19/2018] [Indexed: 06/08/2023]
Abstract
Both plasmon-phonon-polariton (SPP-PHP) modes and phonon-polariton (PHP) modes supported in graphene-coated hexagon boron nitride (h-BN) single nanowire are presented. The field distributions of the lowest 5 order modes of SPP-PHP modes supported in graphene-coated hexagon boron nitride nanowire pairs (SPP-PHP-GHNP) and the lowest 5 order modes of PHP modes supported in graphene-coated hexagon boron nitride nanowire pairs (GHNP) are also demonstrated and analyzed, respectively. The results of numerical calculation show that SPP-PHP-GHNP mode 0 owns the strongest confinement and lowest loss among the lowest 5 order modes of SPP-PHP-GHNP. Furthermore, the field enhancement of SPP-PHP-GHNP mode 0 can reach over 105 by controlling the geometry parameters of GHNP. Meanwhile, the influence of tuning the Fermi level of graphene on the field enhancement is also presented in the paper. The proposed structure may improve the development of graphene-h-BN-based optoelectronic devices.
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Nemnes GA, Mitran TL, Dragoman D. Ballistic transport in graphene Y-junctions in transverse electric field. NANOTECHNOLOGY 2018; 29:355202. [PMID: 29866948 DOI: 10.1088/1361-6528/aaca43] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We investigate the prospects for current modulation in single layer graphene Y-junctions in the ballistic regime, under an external electric field. Overcoming the inability of inducing field effect in graphene nanoribbons by a stacked gate, the proposed in-plane electric field setup enables a controlled current transfer between the branches of the Y-junction. This behavior is further confirmed by changing the angular incidence of the electric field. The ballistic transmission functions are calculated for the three terminal system using the non-equilibrium Green's function formalism, in the framework of density functional theory, under finite bias conditions. The edge currents dominating the transport in zigzag nanoribbons are strongly influenced by the induced dipole charge, facilitating the current modulation even for the metallic-like character of the Y-junctions. Spin polarization effects indicate the possibility of achieving spin filtering even in the absence of the external field provided the antiferromagnetic couplings between the edges are asymptotically set. Overall, our results indicate a robust behavior regarding the tunability of the charge current in the two outlet ports, showing the possibility of inducing field effect control in a single layer graphene system.
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Affiliation(s)
- G A Nemnes
- University of Bucharest, Faculty of Physics, Materials and Devices for Electronics and Optoelectronics Research Center, 077125 Magurele-Ilfov, Romania. Horia Hulubei National Institute for Physics and Nuclear Engineering, 077126 Magurele-Ilfov, Romania
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